Physical downlink control channel and physical hybrid automatic repeat request indicator channel enhancements

ABSTRACT

A wireless transmission system included at least one user equipment and a base station. The base station is operable to form a downlink control information block, modulate the downlink control information, precode the modulated downlink control information, and transmit the precoded, modulated downlink control information on at least one demodulation reference signal antenna port to the at least one user equipment. The precoded, modulated downlink control information is mapped to a set of N 1  physical resource block pairs in a subframe from an orthogonal frequency division multiplexing symbol T 1  to and orthogonal frequency division multiplexing symbol T 2.

CLAIM OF PRIORITY

This application is a continuation of prior application Ser. No.14/679,913, filed Apr. 6, 2015, now U.S. Pat. No. 9,603,141, which is acontinuation of prior application Ser. No. 13/458,410, filed Apr. 27,2012, now U.S. Pat. No. 9,001,756, which claims priority under 35 U.S.C.119(e)(1) to U.S. Provisional Application No. 61/479,655 filed Apr. 27,2011, U.S. Provisional Application No. 61/481,840 filed May 2, 2011,U.S. Provisional Application No. 61/483,848 filed May 9, 2011, U.S.Provisional Application No. 61/525,315 filed Aug. 19, 2011, U.S.Provisional Application No. 61/542,962 filed Oct. 4, 2011 and U.S.Provisional Application No. 61/558,196 filed Nov. 10, 2011.

TECHNICAL FIELD OF THE INVENTION

The technical field of this invention is wireless communication such aswireless telephony.

BACKGROUND OF THE INVENTION

The 3rd Generation Partnership Project Evolved Universal TerrestrialRadio Access (E-UTRA) Long Term Evolution (LTE) Rel. 8 to 10 controlsignals include Physical Control Format Indicator CHannel (PCFICH),Physical Hybrid ARQ Indicator CHannel (PHICH) and Physical DownlinkControl CHannel (PDCCH).

Legacy PDCCH in LTE Rel. 8 to 10 is designed with Cell specificReference Symbols (CRS) based transmission. A PDCCH is scrambled withthe Cell Radio Network Temporary Identifier (C-RNTI) of the user beingscheduled and precoded with 1/2/4 transmit diversity, cross-interleavedwith other PDCCHs and then transmitted in the entire system bandwidth inthe control region of a subframe. The control region contains the firstN Orthogonal Frequency Division Multiplexing (OFDM) symbols in the firstslot of a subframe. The value of N is N=1, 2, 3 or 4 in case of 1.4 MHzbandwidth and is signalled in the PCFICH. Through CRS-based transmitdiversity and cross-interleaving within the system bandwidth, Rel. 10PDCCH exploits spatial and frequency diversity to maximize therobustness of the control signal and ensures its reliable reception andcoverage in a cell. A PDCCH may carry a DL grant or an UL grant.

LTE Rel. 10 introduces a new PDCCH transmission scheme for macro-relaybackhaul link called R-PDCCH. R-PDCCH inherits all the Downlink ControlInformation (DCI) formats of legacy LTE system including DCI 1, 1A, 1B,1C, 2, 2A, 2B, 2C and 4 but relies on Demodulation Reference Signal(DMRS) based transmission instead of CRS based transmit diversity. Thusfor each relay node, a semi-statically configured downlink resource isreserved for the eNB-to-RN link by higher-layer. This resource is usedfor R-PDCCH and R-PDSCH transmission. In the frequency domain thereserved resource features a set of N_(R-PDCCH) resource blocks. In thetime domain the transmission resource features a group of OFDM symbolsin the respective first slot and second slot. The first slot is used forDL grant transmission. The second slot is used for UL granttransmission. The reserved resources of both the first and second slotscan be also used for R-PDSCH in the eNB-to-RN backhaul link, providedthat they are not occupied by R-PDCCH.

When a relay is configured with R-PDCCH with cross-interleaving: R-PDCCHis transmitted with CRS-based transmit diversity according to the sameprocedure as in legacy LTE system, except that interleaving is done inthe virtual system bandwidth of N_(R-PDCCH) Resource Blocks (RBs).

When a relay is configured with R-PDCCH without cross-interleaving:R-PDCCH can be transmitted with CRS-based transmit diversity in theN_(R-PDCCH)×RBs. Alternatively, R-PDCCH can be transmitted withDMRS-based rank-1 precoding in the NR-PDCCH RBs, on antenna port 7 witha scrambling sequence ID (SCID) of 0. The actual number of PhysicalResource Blocks (PRBs) used for R-PDCCH depends on the R-PDCCHaggregation level and candidate index.

SUMMARY OF THE INVENTION

A wireless transmission system included at least one user equipment anda base station. The base station is operable to form a downlink controlinformation block, modulate the downlink control information, precodethe modulated downlink control information, and transmit the precoded,modulated downlink control information on at least one demodulationreference signal antenna port to the at least one user equipment. Theprecoded, modulated downlink control information is mapped to a set ofN1 physical resource block pairs in a subframe from an orthogonalfrequency division multiplexing symbol T1 to and orthogonal frequencydivision multiplexing symbol T2.

The downlink control information is a downlink assignment or an uplinkgrant. The base station transmits the precoded, modulated downlinkcontrol information on one demodulation reference signal antenna port.The base station transmits the precoded, modulated downlink controlinformation on more than one demodulation reference signal antennaports. The base station configures the at least one demodulationreference signal antenna port by higher-layer signaling. The basestation scrambles the at least one demodulation reference signal antennaport by a scrambling sequence configured by higher-layer signaling. Thebase station dynamically signals the at least one demodulation referencesignal antenna port and the corresponding scrambling sequence by aD-PDCCH-config grant, which is modulated and transmitted from the saidbase station based on cell specific reference signal.

The base station fixed or semi-statically configures the orthogonalfrequency division multiplexing symbol T1 by higher-layer signaling. Theorthogonal frequency division multiplexing symbol T1 is a firstorthogonal frequency division multiplexing symbol outside a legacycontrol region. The base station fixed or semi-statically configures theorthogonal frequency division multiplexing symbol T2 by higher-layersignaling. The orthogonal frequency division multiplexing symbol T2 isdependent on a category of a corresponding user equipment. The basestation is further operable to determine the orthogonal frequencydivision multiplexing symbol T2 by the user equipment and transmits tothe base station in the uplink.

The base station configures the set of N1 physical resource block pairsby higher-layer signaling. The base station transmits at least one layerof data stream from the base station to the at least one user equipmentin the subframe. The scheduling information of the at least one layer ofdata stream is included in the downlink control information.

In the wireless transmission system the base station forms a downlinkcontrol information block including unmodulated information bits and adownlink acknowledge/not acknowledge bit.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of this invention are illustrated in thedrawings, in which:

FIG. 1 illustrates an exemplary prior art wireless communication systemto which this application is applicable;

FIG. 2 shows the Evolved Universal Terrestrial Radio Access (E-UTRA)Time Division Duplex (TDD) frame structure of the prior art;

FIG. 3 illustrates a comparison of a R-PDCCH downlink grant and aR-PDCCH uplink grant;

FIG. 4 illustrates the cases of a D-PDCCH-config-grant in a differingsubframe than a D-PDCCH and a D-PDCCH-config-grant in the same subframeas a D-PDCCH;

FIG. 5 illustrates the region size in the time domain known as thestarting OFDM symbol of a D-PDCCH;

FIG. 6A illustrates rate matching around REs containing D-PDCCH;

FIG. 6B illustrates rate matching around OFDM symbols.

FIG. 7 illustrates a the first scenario illustrated in which DL grantsare absent and the user equipment assumes that uplink grants are carriedacross both slots of the VRB pairs configured for D-PDCCH transmission.

FIGS. 8A and 8B illustrate a second scenario in which downlink grantsare present, FIG. 8A illustrates a case where grants do not cross fromslot 0 to slot 1 and FIG. 8B illustrates a case where grants cross fromslot 0 to slot 1;

FIG. 9A illustrates rate matching around resource elements containingD-PDCCH for PDSCH mapping with slot-based splitting of UL and DL grants;

FIG. 9B illustrates rate matching around OFDM symbols for PDSCH mappingwith slot-based splitting of uplink and downlink grants;

FIG. 10A illustrates joint encoding of downlink DCI and HI;

FIG. 10B illustrates separate encoding of downlink DCI and HI;

FIG. 11 illustrates the case of a non-backward compatible CC without alegacy control region; and

FIG. 12 is a block diagram illustrating internal details of a basestation and a mobile user equipment in the network system of FIG. 1suitable for implementing this invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows an exemplary wireless telecommunications network 100. Theillustrative telecommunications network includes base stations 101, 102and 103, though in operation, a telecommunications network necessarilyincludes many more base stations. Each of base stations 101, 102 and 103(eNB) are operable over corresponding coverage areas 104, 105 and 106.Each base station's coverage area is further divided into cells. In theillustrated network, each base station's coverage area is divided intothree cells. Handset or other user equipment (UE) 109 is shown in Cell A108. Cell A 108 is within coverage area 104 of base station 101. Basestation 101 transmits to and receives transmissions from UE 109. As UE109 moves out of Cell A 108 and into Cell B 107, UE 109 may be handedover to base station 102. Because UE 109 is synchronized with basestation 101, UE 109 can employ non-synchronized random access toinitiate handover to base station 102.

Non-synchronized UE 109 also employs non-synchronous random access torequest allocation of up-link 111 time or frequency or code resources.If UE 109 has data ready for transmission, which may be traffic data,measurements report, tracking area update, UE 109 can transmit a randomaccess signal on up-link 111. The random access signal notifies basestation 101 that UE 109 requires up-link resources to transmit the UEsdata. Base station 101 responds by transmitting to UE 109 via down-link110, a message containing the parameters of the resources allocated forUE 109 up-link transmission along with a possible timing errorcorrection. After receiving the resource allocation and a possibletiming advance message transmitted on down-link 110 by base station 101,UE 109 optionally adjusts its transmit timing and transmits the data onup-link 111 employing the allotted resources during the prescribed timeinterval.

Base station 101 configures UE 109 for periodic uplink soundingreference signal (SRS) transmission. Base station 101 estimates uplinkchannel quality information (CSI) from the SRS transmission.

FIG. 2 shows the Evolved Universal Terrestrial Radio Access (E-UTRA)time division duplex (TDD) Frame Structure. Different subframes areallocated for downlink (DL) or uplink (UL) transmissions. Table 1 showsapplicable DL/UL subframe allocations.

TABLE 1 Con- Switch-point Sub-frame number figuration periodicity 0 1 23 4 5 6 7 8 9 0  5 ms D S U U U D S U U U 1  5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms D S U U U D D D D D 4 10 ms D S U U DD D D D D 5 10 ms D S U D D D D D D D 6 10 ms D S U U U D S U U D

In this invention the R-PDCCH format of relay backhaul link in Rel. 10is extended to regular eNB-to-UE PDCCH transmission in Rel. 11. Thisallows DMRS-based PDCCH transmission in Rel. 11 in addition to CRS-basedPDCCH transmission. This is called D-PDCCH (DMRS-PDCCH). The D-PDCCHinherits all the characteristics of the R-PDCCH except for the newproposals outlined below. The current R-PDCCH design only supportsrank-1 transmission of R-PDCCH and is confined to antenna port 7 with aSCID of 0. Thus the prior art downlink (DL) RB can be only used to senda single R-PDCCH to schedule 1 user.

It is possible to allow Multiuser, Multiple Input, Multiple Output(MU-MIMO) transmission of PDCCH in the Rel. 11 time frame so that PDCCHsof two or more users can be transmitted in the same frequency. Such usermultiplexing in the control region is an effective means to increase thecontrol channel capacity for Rel. 11. The control capacity can be aserious problem in a Coordinated Multi-point (CoMP) scenario where thelow-power remote radio heads (RRHs) do not have their own cell ID andtherefore do not create additional control channels. This is in contrastto a scenario where all RRHs are stand-alone cells and have their owncontrol resources. Thus increasing the control capacity through MU-MIMOspatial multiplexing can be very helpful in the common cell-ID RRHscenario.

This invention includes following design options for DMRS-based PDCCHenhancements. In a first embodiment a UE configured to receive its PDCCHwith DMRS-based precoding (D-PDCCH), the D-PDCCH is transmitted onantenna port 7 or 8. The D-PDCCH is scrambled with a SCID of 0 or 1. TheUE-specific antenna port (7 or 8) and SCID (0 or 1) of a D-PDCCH issemi-statically configured by higher-layer Radio Resource Control (RRC)signaling. Thus a UE can be configured to decode its D-PDCCH on antennaport 8 with a SCID of 0. The DL grant and UL grant can besemi-statically configured with the same/different antenna ports and/orSCID. Thus a UE may be configured to decode DL grant in D-PDCCH onantenna port 7, and decode UL grant on antenna port 8.

In an alternative embodiment the UE-specific antenna port and SCID forD-PDCCH are dynamically signaled by a D-PDCCH-config-grant. TheD-PDCCH-config-grant dynamically signals the antenna port and SCID ofthe corresponding D-PDCCH. The UE first decodes the D-PDCCH-config-grantto obtain the antenna Port (AP) and SCID information, then proceeds toblind decoding of D-PDCCH. The D-PDCCH-config-grant is transmitted withlegacy PDCCH format such as DCI 1C with CRS based transmission. TheD-PDCCH-configuration grant is transmitted L subframes prior to thecorresponding D-PDCCH. If L is 0, then D-PDCCH-configuration-grant andthe corresponding D-PDCCH are transmitted in the same subframe. This canbe quite challenging to the UE because the number of blind decodingswill significantly increase, while the memory requirement for controldecoding will be more stringent. On the other hand L greater than 0appears desirable from the UE blind decoding and memory perspective, butthe scheduling latency will be increased compared to legacy PDCCH.

It is possible to support rank greater than 1 transmission of D-PDCCH toincrease control channel capacity. This comes at the risk of reducedD-PDCCH coverage. In one embodiment, the transmission rank, set of DMRSantenna ports and SCID of a D-PDCCH are UE-specific and semi-staticallyconfigured by the higher layer. For example a UE can be configured toreceive D-PDCCH with rank 1 transmission on a single antenna port 7 or8, scrambled by a pre-defined SCID of 0 or 1 and all configured byhigher-layer. In a second example, a UE can be configured by higherlayer to receive D-PDCCH with rank greater than 1, using spatialmultiplexing on antenna ports (7, . . . , 7+R−1) with a SCID of 0. Inanother embodiment, the transmission rank, antenna ports and SCID aredynamically configured with the D-PDCCH-config-grant as described above.

In Rel. 10 R-PDCCH spatial multiplexing of the R-PDSCH and R-PDCCHcarrying a DL grant for the same relay is not supported. Thus if the RNreceives a resource allocation for R-PDSCH that overlaps a PRB pair inwhich a DL grant R-PDCCH is detected in the first slot, the RN nodeshall assume that there is no R-PDSCH transmission for it in the firstslot of that PRB pair. Thus the R-PDCCH carrying a DL grant and R-PDSCHcan not overlap in the frequency domain in the first slot, even if theirantenna ports are orthogonal such as R-PDCCH transmitted on AP 7 andR-PDSCH transmitted on AP 8.

To the contrary spatial multiplexing of R-PDSCH and R-PDCCH carrying ULgrant for the same relay is not precluded in Rel. 10. An R-PDCCHcarrying UL grant can be transmitted on AP7 in the second slot, whileR-PDSCH can be transmitted on the same PRB in the second slot. In thiscase R-PDSCH can be scheduled on a different antenna port than theR-PDSCH carrying UL grant such as AP 8. Spatial multiplexing of R-PDSCHfor a relay via AP 8 and R-PDCCH carrying DL grant for a different relayvia AP 7 is not precluded in Rel. 10 backhaul link.

If spatial multiplexing of PDSCH data and D-PDCCH carrying DL grant forthe same UE is desirable in Rel. 11, then the following multiplexingsolutions are possible.

The PDSCH of a UE overlaps in one or more PRB in which a DL grant(D-PDCCH) is detected for this UE. If the D-PDCCH and the correspondingPDSCH are assigned to different antenna port and/or SCID, the UE mayassume that PDSCH is transmitted in the PRB in which the D-PDCCH isdetected. For example if D-PDCCH is transmitted on AP 7 with a SCID of 0and the UE receives a DL resource allocation for 1-layer beamforming onAP 8 and a SCID of 0, then UE may assume that PDSCH can be transmittedin a PRB overlapping with the D-PDCCH.

In another embodiment, if multiple antenna ports are assigned for PDSCHtransmission, the UE may assume that the PDSCH is transmitted in a PRBoverlapping with D-PDCCH, if the antenna port and/or SCID are differentfor the PDSCH and D-PDCCH. For example if D-PDCCH is transmitted on AP 7with a SCID of 0 and the UE receives a DL grant indicating rank-2transmission on AP 7 and AP 8 with a SCID of 0, then in a PRBoverlapping with D-PDCCH, UE may assume that the layer on antenna portAP 7 is not transmitted while the layer on antenna port AP 8 istransmitted.

For Rel. 10 R-PDCCH the control region size in the time domain of thestarting/ending OFDM symbols is semi-statically configured by higherlayer RRC signaling. A DL grant R-PDCCH is transmitted in the firstslot. A fixed control region size is used where the starting OFDM symbolin the first slot is fixed to be OFDM symbol 3. The unused OFDM symbolsare intended for the DL control transmission via Multimedia Broadcastmulticast service Single Frequency Network (MBSFN) subframes from the RNto UE. These also serve as a tool for interference management of thecontrol signaling when cross-carrier scheduling is used.

TABLE 2 End symbol Configuration DL-StartSymbol index 0 1 6 1 2 6 2 3 6A UL grant R-PDCCH is transmitted in the second slot, always startingfrom OFDM symbol 0. This allows switching between donor-eNB-to-RN andRN-to-UE transmission.

TABLE 3 Start End symbol symbol Configuration index index 0 0 6 1 0 5

For D-PDCCH, this invention includes two possible types of embodiment.The first embodiment follows the slot-based splitting for DL and ULgrants from R-PDCCH. The second embodiment abolishes this restriction.

For this first embodiment with slot-based splitting for DL and UL grantsbased on R-DPCCH, this is DL grant which occupies the first slot of asubframe. For Rel. 11 D-PDCCH, the control region size in the timedomain, also known as the starting OFDM symbol of a D-PDCCH, can bedetermined as shown in FIG. 4. In a first alternative the starting OFDMsymbol of D-PDCCH for a DL grant is fixed such as OFDM symbol 3 in thefirst slot which is the same as R-PDCCH in Rel. 10. In a secondalternative the starting OFDM symbol of D-PDCCH for a DL grant is fixedfor a given configuration. Thus the starting OFDM symbol of D-PDCCH(OFDM symbol 0, 1, 2 or 3) is semi-statically configured. This maysimply reuse the set of values in Rel. 10 R-PDCCH. A preferredalternative is to add an additional starting OFDM symbol 0.

In an additional embodiment, if a UE receives a DL assignment on D-PDCCHand if the UE detects via PCFICH on its legacy control region that thenumber of OFDM symbols is strictly smaller than the starting symbol forD-PDCCH, then the UE shall assume that PDSCH is also present on the OFDMsymbols between the last symbol of the legacy PDCCH region and the firstsymbol of the D-PDCCH. The UE shall also assume that its PDSCH is mappedaround the OFDM symbols containing D-PDCCH.

For either the first or second alternative above if a UE receives a DLassignment on D-PDCCH and if the UE detects via PCFICH on its legacycontrol region that the number of OFDM symbols is strictly smaller thanthe starting symbol for D-PDCCH, then the UE assumes one of thefollowing two embodiment for determining the resources on which itsPDSCH is mapped. If the DL-assignment on D-PDCCH overlaps with the DLassignment for PDSCH, the UE assumes that in the overlapping PRBs, thePDSCH is also present on the OFDM symbols between the last symbol of thelegacy PDCCH region and the first symbol of the D-PDCCH. The UE alsoassumes that within the overlapping PRB assignment, its PDSCH is mappedaround the resource elements containing the D-PDCCH. In the secondalternative if the DL-assignment on D-PDCCH overlaps with the DLassignment for PDSCH, the UE assumes that its PDSCH is also present onthe OFDM symbols between the last symbol of the legacy PDCCH region andthe first symbol of the D-PDCCH. The UE also assumes that its PDSCH ismapped around the OFDM symbols containing the D-PDCCH.

FIGS. 6A and 6B illustrate two alternative assignments for PDSCH mappingwith slot-based splitting of UL and DL grants. FIG. 6A illustrates ratematching around REs containing D-PDCCH. FIG. 6B illustrates ratematching around OFDM symbols.

Table 4 shows the principle behind second alternative described above.

TABLE 4 End symbol Configuration DL-StartSymbol index 0 0 6 1 1 6 2 2 63 3 6

In a third alternative the starting OFDM symbol of a D-PDCCH for a DLgrant is dynamically and implicitly signaled depending on the legacycontrol region size signaled in PCFICH. First, the UE reads the PCFICHto determine the legacy control region span in the time domain such asincluding 1, 2 or 3 OFDM symbols. Secondly, the starting OFDM symbol ofD-PDCCH is the first OFDM symbol outside of the legacy control region.In an example the legacy control region size of a cell is 2 OFDM symbolswith a PCFICH of 2. After the UE reads the PCFICH, it determines thatD-PDCCH starts from the third OFDM symbol (OFDM symbol 2). This controlsresources for legacy LTE terminals and Rel. 11 terminals can bedynamically adjusted based on the percentage of legacy UEs and Rel. 11UEs in the deployment. As legacy UE gradually phase out in the network,the network can configure a smaller legacy control region such as aPCFICH of 1) and assign more resources for Rel. 11 D-PDCCH.

In a fourth alternative the D-PDCCH starts from OFDM symbol 0 and mayoccupy the entire PRB in the first slot. Thus the D-PDCCH is allowed toextend into the legacy control region in the time domain. In thisalternative it is possible for a legacy PDCCH and D-PDCCH to collide.The eNB scheduler must ensure that the D-PDCCH and legacy PDCCH (Rel.8/9/10) do not overlap.

The following describes the configuration for UL grant which takes placein the second slot of a subframe. The relevant component is the endingOFDM symbol. The ending OFDM symbol of a D-PDCCH can be the last OFDMsymbol of the first slot. This invention differs from the Rel. 10R-PDCCH principle because the switching time mentioned above is notneeded for D-PDCCH. The start and end symbol index for the second slotare always 0 and 6, respectively.

The following describes the conditional assignment of UL grant either inboth slots or only in the second slot. A conditional assignment of ULgrant is defined based on whether or not DL grants are transmitted inthe first slot of same subframe. Assume that DL grants if transmittedare carried in the first slot of Virtual Resource Block (VRB) pairsconfigured to carry D-PDCCH. There are two scenarios. In the firstscenario illustrated in FIG. 7 DL grants are absent and the UE assumesthat UL grants, if transmitted on D-PDCCH, are carried across both slotsof the VRB pairs configured for D-PDCCH transmission. In the secondscenario illustrated in FIGS. 8A and 8B DL grants are present. It isdesirable for channel estimation accuracy to preclude the case of PDSCHbeing transmitted in the same VRB pairs containing D-PDCCH. In thisinvention the UE shall not expect to receive a DL resource allocationwhich overlaps VRB pair(s) in a downlink assignment is detected in thefirst slot. This precludes multiplexing of PDSCH and D-PDCCH containinga downlink assignment in the same VRB pair(s). There are two candidateUE behaviors for determining whether a UL grant is transmitted in thesame VRB pair(s) as a DL grant. In the first alternative illustrated inFIG. 8A if both DL grant and UL grants are transmitted for the same UEon the D-PDCCH, the UE assumes that the UL grants can be carried in thesecond slot of only those VRB pairs in which the first slot carries a DLgrant. Thus the aggregation level for UL grant is less than or equal tothe aggregation level of the DL grant. This permits the possibility thatthe aggregation levels for UL grant and DL grants for the same UE arealways the same. In the second alternative illustrated in FIG. 8B ifboth DL grant and UL grants are transmitted for the same UE on theD-PDCCH, the UE assumes that the UL grant is present at least in thesecond slot of those VRB pairs in which the first slot carries a DLgrant. Thus UL grants may be transmitted in one slot and/or two slotsdepending on whether or not the VRB pairs carrying UL grant carry DLgrants.

The second embodiment does not include slot-based splitting for DL andUL grants. While the slot-based splitting for DL and UL grants ispossible (above firs embodiment), such restriction is unnecessary forD-PDCCH since the DL and UL traffics are asymmetric for typically PDSCHtransmission unlike that in the relaying operations. Such a designremoves the slot-based splitting for DL and UL grants. Thus DL and ULgrants may occupy the same set of OFDM symbols within a subframe. The DLand UL grants can coexist and be searched together within the same setof configured D-PDCCH resources in time and frequency domains such asrespective across OFDM symbols and frequency PRBs or PRB pairs. The OFDMsymbol for a subframe starts for D-PDCCH. The setup mechanism outlinedabove can be applied without the restriction of DL-grant-only usage. Thestarting OFDM symbol for D-PDCCH which can carry DL and/or UL grant(s)can be fixed to a value (symbol 0, 1, 2, or 3), semi-staticallyconfigured or dynamically/implicitly signaled.

Next the ending OFDM symbol is selected. There are two alternatives. Inthe first alternative the D-PDCCH ends in a designated OFDM symbolwithin a subframe. The designated OFDM symbol is not the last OFDMsymbol within the subframe. For example it is possible to designate theending OFDM symbol to be within the first slot for both DL and UL grantslike the last OFDM symbol in the first slot illustrated in FIG. 5 forboth DL and UL grants. This alternative allows a UE to performmicro-sleep (power saving) when no DL grant is detected. Thisalternative offers a more relaxed timing budget for the UE because theUE is able to start PDSCH demodulation/decoding earlier. The ending OFDMsymbol can either be fixed (not configurable) or semi-staticallyconfigured via RRC signaling or SIBx carried via D-BCH. The semi-staticconfiguration requires the UE to decode either a PDSCH transmission or abroadcast paging grant. This can be accomplished using a Rel. 8mechanism. This may reduce the benefit of introducing a new D-PDCCH. Anon-configurable ending OFDM symbol seems to be sufficient consideringthat the PRB/PRB pair allocation for D-PDCCH can be semi-staticallyconfigured.

In the second alternative the D-PDCCH ends in the last OFDM symbolwithin a subframe. This is a pure Frequency Division Multiplexing (FDM)structure of the control channel. One D-PDCCH either a DL or an UL grantexpands across the entire subframe. Thus both PRBs in a PRB pair areused for D-PDCCH transmission. One advantage of this design is a morerobust demodulation performance in high-mobility deployment scenariobecause demodulation of PDCCH can use the DMRS in both slots in asubframe. This is important because the D-PDCCH will be used for regularUE scheduling instead of only for relays.

For either the first or second alternative above if a UE receives a DLassignment on D-PDCCH and if the UE detects via PCFICH on its legacycontrol region that the number of OFDM symbols is strictly smaller thanthe starting symbol for D-PDCCH, then the UE assumes one of thefollowing two embodiment for determining the resources on which itsPDSCH is mapped. If the DL-assignment on D-PDCCH overlaps with the DLassignment for PDSCH, the UE assumes that in the overlapping PRBs, thePDSCH is also present on the OFDM symbols between the last symbol of thelegacy PDCCH region and the first symbol of the D-PDCCH. The UE alsoassumes that within the overlapping PRB assignment, its PDSCH is mappedaround the resource elements containing the D-PDCCH. In the secondalternative if the DL-assignment on D-PDCCH overlaps with the DLassignment for PDSCH, the UE assumes that its PDSCH is also present onthe OFDM symbols between the last symbol of the legacy PDCCH region andthe first symbol of the D-PDCCH. The UE also assumes that its PDSCH ismapped around the OFDM symbols containing D-PDCCH.

FIGS. 9A and 9B illustrate two alternative assignments for PDSCH mappingwith slot-based splitting of UL and DL grants. FIG. 9A illustrates ratematching around REs containing D-PDCCH. FIG. 9B illustrates ratematching around OFDM symbols.

Prior art LTE Rel. 8/9/10 systems use synchronous Hybrid AutomaticRepeat Request (HARQ) for UL Synchronization Channel (SCH)transmissions. For an UL-SCH transmission on the PUSCH in subframe n aHARQ-ACK is transmitted on either the PHICH or implicitly in an UL grantin subframe n+k, where k−4 for FDD. The Rel. 10 PHICH region multiplexedacross the system bandwidth has either the first 1 or 3 OFDM symbols.For this invention the UE is configured to receive DL assignments or ULgrants in the D-PDCCH region. There are a few possibilities forreceiving DL HARQ-ACK (ACK or NACK) signaling in response to a PUSCHtransmission as described below.

In a first scheme if there is a legacy control region of at least 1 OFDMsymbol, then the PHICH for all UEs can be transmitted as in the priorart Rel. 8/9/10. In this case, the PHICH resource allocation is basedon: a) the PHICH duration Normal or Extended PHICH; b) the parameter,Ng, both the above parameters are signaled via the PBCH; c) the lowestindexed PRB in the first slot of the corresponding PUSCH transmission;and d) the cyclic shift field of the uplink DM-RS associated with thecorresponding UL DCI format.

In a second scheme regardless of the existence of a legacy controlregion it may be preferable to have a unified design of UE-specificDMRS-based DL control signaling for both PDCCH and PHICH. For anon-backward compatible DL component carrier there may not be a legacycontrol region. There are two possibilities for this alternative. In thefirst possibility the DL HARO-ACK is implicitly transmitted in the ULgrant via adaptive retransmission as in earlier releases. With thisapproach HARQ-ACK signaling is dependent on the eNB scheduling an ULgrant in subframe n+k if a PUSCH was transmitted in subframe n. Thesecond possibility is dependent on the probability of an UL grant theHARQ-ACK signaling efficiency can be increased by also encoding theHARQ-ACK indicator (HI) in a DL assignment. The HI can be jointlyencoded with the DL DCI format or it can be separately encoded and thenconcatenated with the encoded DCI format before modulation. Thesepossibilities are illustrated in FIGS. 9A and 9B. The UE behavior is asfollows. In subframe n+k the UE searches in its search space for eitherUL grants or DL assignments. If an UL grant is detected the UE uses theinformation contained in the UL grant for (re)transmission. If a DLassignment is detected and no UL grant is detected in a subframe n+k,the UE retransmits the negatively acknowledged transport block(s), ifany. If neither an UL grant nor a DL assignment is detected the UE doesnot retransmit. Thus the UE assumes an implicit ACK was received.However, the UE does not flush the HARQ buffer.

Between separate and joint encoding of DL DCI and HI, separate encodingis preferred because it allows the possibility of extracting HIseparately from DCI before performing channel encoding. For alternativethe configuration of a DMRS-based PHICH region is UE-specific and can bedifferent from the configuration of the D-PDCCH. For example a UE can beconfigured to monitor for DL/UL assignments in the D-PDCCH region and tomonitor for DL HARQ in the Rel. 8/9/10 PHICH region, or alternativelycan be configured to monitor for DL/UL assignments and DL HARQ in adedicated D-PDCCH region.

If HI and DL DCI are encoded separately, there are two additionalalternatives. In the first alternative the DCI is rate-matched aroundHI. HI is placed at a pre-designated location within the allocatedresource. The D-PDCCH signal containing DCI is mapped around theresource elements containing the HI. In a first sub-alternative the HImay be mapped to the resource grid on the starting resource elements(whose number is dependent on the payload size for HI and the modulationmapping used for HI) of the set of VRBs for which D-PDCCH is configured.In a second sub-alternative the HI is mapped to a set of resourceelements (RE) whose location is semi-statically signaled to the UE.

This first alternative ensures that the encoded HI is not combined withDL DCI prior to modulation mapping to Quadrature Phase Shift Keying(QPSK) symbols and mapping to CCEs. This avoids any potentiallyundesirable dependence of the HI being extracted on whether or not theblind decoding for PDCCH is complete. This first alternative allows theUE to detect the location of its HI prior to starting blind decodes. Thepayload of HI is fixed and so is the channel coding rate thus reusingthe prior art Rel. 8 principle. For HI, power control is used to ensuregood coverage. The UE is aware of the payload size of HI because itknows how many codewords were transmitted over uplink in the most recenttransmission.

There are the following further sub-alternatives regarding signalgeneration for HI. In the first further sub-alternative during thefrequency first mapping which occurs during non-cross interleaving, theprecoded HI is mapped on to a set of resource elements (the startingresource elements or a set of resource elements location that aresignaled to the UE via higher layer signaling) on the set of VRBs forwhich D-PDCCH is configured. The UE need only search this set ofdesignated resource elements within each candidate D-PDCCH VRB fordetermining the HI if present. In the second further sub-alternative theD-PDCCH is mapped around the HI signal just as in the prior art Rel. 8.This avoids the undesirable dependence of HI the being extracted onwhether or not the blind decoding is complete. Once the UE finishesdetermining the start and end location of the HI, it can start blinddecoding for extracting its control payload.

In the second alternative for coding the HI and DL DCI separately, theDCI is not rate-matched around HI. The UE assumes that the DCIinformation signal are never mapped around resource elements mapped toHI. In this case, HI is placed at any pre-designated location in theresource element grid which cannot overlap with the transmission of theD-PDCCH containing DCI data. In a first sub-alternative the HI locationsare semi-statically signaled to the UE such that DCI mapping will neveroccur across resource element boundaries containing HI. In a secondsub-alternative the HI locations are fixed and based on the largestpossible DCI payload corresponding to the downlink system bandwidth.This ensures that DCI mapping will never occur across resource elementscontaining HI.

A third scheme allocates a new semi-statically signaled PHICH regionwhich consists of one or more PRBs in the first slot of the subframe.This region is common to all UEs and the UE can use a similar prior artRel. 8/9/10 linkage between PHICH resource and lowest indexed PRB/cyclicshift index. This may result in some restriction in eNB scheduling inthe PDSCH region. This prevents using UE-specific DMRS for demodulation.Thus this is suitable for the case of a non-backward compatible CCwithout a legacy control region as shown in FIG. 11. In a differentembodiment the PHICH region is FDM multiplexed in a subframe where thePHICH region occupies both slots of a subframe.

The following is a description of HI transmission via DM-RS precoding.For a UE configured to receive its PDCCH with DMRS-based precodingD-PDCCH, the HI is transmitted on antenna port 7 or 8. The UE-specificantenna port 7 or 8 and SCID of 0 or 1 of a HI is semi-staticallyconfigured by higher-layer RRC-signaling. For example, a UE may beconfigured to decode its HI on antenna port 8. It is possible to supportrank greater than 1 transmission of HI in case ACK-NAK for multipleuplink codewords if desired. The transmission rank and set of DMRSantenna ports are UE-specific and semi-statically configured by thehigher layer. In a first example the UE is configured to receive HI withrank of 1 transmission on a single antenna port 7 or 8 configured byhigher-layer. In a second example the UE is configured by higher layerto receive HI with rank greater than 1 spatial multiplexing on antennaports (7, . . . , 7+R−1).

The following is a description of ePDCCH rate-matching around CRSpositions of a set of neighboring cells. In this invention ePDCCHtransmission can be configured via higher-layer signaling to be muted(rate-matched around) on the CRS positions of a set of neighboring cell(s). Such ePDCCH muting is beneficial in range-extended het-nets wherethe CRS transmissions of an aggressor cell(s) required for legacysupport can deteriorate reception at a victim UE that is receiving itsePDCCH from a weaker cell even during almost blank subframes of theaggressor cell(s). By muting ePDCCH on the CRS positions of the strongercell, the weaker cell can ensure that the rate-matched ePDCCH isreliably received at the victim UEs. In this invention the zero-powerePDCCH may be configured via higher-layer signaling. Alternately thev-shifts or the cell IDs of the cells on whose CRS positions the ePDCCHis rate-matched are signaled via higher-layer. In a further alternativeupon configuration with zero-power ePDCCH on CRS positions of a set ofneighboring cell(s), the UE shall assumes that its ePDCCH israte-matched around the CRS locations of a set of neighboring cell(s).

FIG. 12 is a block diagram illustrating internal details of an eNB 1002and a mobile UE 1001 in the network system of FIG. 1. Mobile UE 1001 mayrepresent any of a variety of devices such as a server, a desktopcomputer, a laptop computer, a cellular phone, a Personal DigitalAssistant (PDA), a smart phone or other electronic devices. In someembodiments, the electronic mobile UE 1001 communicates with eNB 1002based on a LTE or Evolved Universal Terrestrial Radio Access Network(E-UTRAN) protocol. Alternatively, another communication protocol nowknown or later developed can be used.

Mobile UE 1001 comprises a processor 1010 coupled to a memory 1012 and atransceiver 1020. The memory 1012 stores (software) applications 1014for execution by the processor 1010. The applications could comprise anyknown or future application useful for individuals or organizations.These applications could be categorized as operating systems (OS),device drivers, databases, multimedia tools, presentation tools,Internet browsers, emailers, Voice-Over-Internet Protocol (VOIP) tools,file browsers, firewalls, instant messaging, finance tools, games, wordprocessors or other categories. Regardless of the exact nature of theapplications, at least some of the applications may direct the mobile UE1001 to transmit UL signals to eNB (base-station) 1002 periodically orcontinuously via the transceiver 1020. In at least some embodiments, themobile UE 1001 identifies a Quality of Service (QoS) requirement whenrequesting an uplink resource from eNB 1002. In some cases, the QoSrequirement may be implicitly derived by eNB 1002 from the type oftraffic supported by the mobile UE 1001. As an example, VOIP and gamingapplications often involve low-latency uplink (UL) transmissions whileHigh Throughput (HTP)/Hypertext Transmission Protocol (HTTP) traffic caninvolve high-latency uplink transmissions.

Transceiver 1020 includes uplink logic which may be implemented byexecution of instructions that control the operation of the transceiver.Some of these instructions may be stored in memory 1012 and executedwhen needed by processor 1010. As would be understood by one of skill inthe art, the components of the uplink logic may involve the physical(PHY) layer and/or the Media Access Control (MAC) layer of thetransceiver 1020. Transceiver 1020 includes one or more receivers 1022and one or more transmitters 1024.

Processor 1010 may send or receive data to various input/output devices1026. A subscriber identity module (SIM) card stores and retrievesinformation used for making calls via the cellular system. A Bluetoothbaseband unit may be provided for wireless connection to a microphoneand headset for sending and receiving voice data. Processor 1010 maysend information to a display unit for interaction with a user of mobileUE 1001 during a call process. The display may also display picturesreceived from the network, from a local camera, or from other sourcessuch as a Universal Serial Bus (USB) connector. Processor 1010 may alsosend a video stream to the display that is received from various sourcessuch as the cellular network via RF transceiver 1020 or the camera.

During transmission and reception of voice data or other applicationdata, transmitter 1024 may be or become non-synchronized with itsserving eNB. In this case, it sends a random access signal. As part ofthis procedure, it determines a preferred size for the next datatransmission, referred to as a message, by using a power threshold valueprovided by the serving eNB, as described in more detail above. In thisembodiment, the message preferred size determination is embodied byexecuting instructions stored in memory 1012 by processor 1010. In otherembodiments, the message size determination may be embodied by aseparate processor/memory unit, by a hardwired state machine, or byother types of control logic, for example.

eNB 1002 comprises a Processor 1030 coupled to a memory 1032, symbolprocessing circuitry 1038, and a transceiver 1040 via backplane bus1036. The memory stores applications 1034 for execution by processor1030. The applications could comprise any known or future applicationuseful for managing wireless communications. At least some of theapplications 1034 may direct eNB 1002 to manage transmissions to or frommobile UE 1001.

Transceiver 1040 comprises an uplink Resource Manager, which enables eNB1002 to selectively allocate uplink Physical Uplink Shared CHannel(PUSCH) resources to mobile UE 1001. As would be understood by one ofskill in the art, the components of the uplink resource manager mayinvolve the physical (PHY) layer and/or the Media Access Control (MAC)layer of the transceiver 1040. Transceiver 1040 includes at least onereceiver 1042 for receiving transmissions from various UEs within rangeof eNB 1002 and at least one transmitter 1044 for transmitting data andcontrol information to the various UEs within range of eNB 1002.

The uplink resource manager executes instructions that control theoperation of transceiver 1040. Some of these instructions may be locatedin memory 1032 and executed when needed on processor 1030. The resourcemanager controls the transmission resources allocated to each UE 1001served by eNB 1002 and broadcasts control information via the PDCCH.

Symbol processing circuitry 1038 performs demodulation using knowntechniques. Random access signals are demodulated in symbol processingcircuitry 1038.

During transmission and reception of voice data or other applicationdata, receiver 1042 may receive a random access signal from a UE 1001.The random access signal is encoded to request a message size that ispreferred by UE 1001. UE 1001 determines the preferred message size byusing a message threshold provided by eNB 1002. In this embodiment, themessage threshold calculation is embodied by executing instructionsstored in memory 1032 by processor 1030. In other embodiments, thethreshold calculation may be embodied by a separate processor/memoryunit, by a hardwired state machine, or by other types of control logic,for example. Alternatively, in some networks the message threshold is afixed value that may be stored in memory 1032, for example. In responseto receiving the message size request, eNB 1002 schedules an appropriateset of resources and notifies UE 1001 with a resource grant.

What is claimed is:
 1. A method of operating a user equipment (UE),comprising: configuring the user equipment (UE) to receive aDemodulation Reference Signal (DMRS)-based physical downlink controlchannel (D-PDCCH), wherein the D-PDCCH is scrambled based on a parameterconfigured via Radio Resource Control (RRC) signaling.
 2. A method ofoperating a user equipment (UE), comprising: configuring the userequipment (UE) to receive a Demodulation Reference Signal (DMRS)-basedphysical downlink control channel (D-PDCCH), wherein the D-PDCCH isscrambled with a scrambling sequence ID (SCID) of 0 or 1, wherein theuser equipment (UE) is configured to decode the D-PDCCH on antenna port8 with a SCID of 0, and wherein the user equipment (UE) is configured todecode a downlink grant in D-PDCCH on a first antenna port, and decodean uplink grant on a second antenna port.
 3. The method of claim 2wherein the first antenna port is antenna port 7 and the second antennaport is antenna port
 8. 4. The method of claim 3, wherein the userequipment (UE)-specific antenna port and SCID for D-PDCCH aredynamically signaled by a D-PDCCH-configuration-grant.
 5. The method ofclaim 4, wherein the D-PDCCH-configuration-grant dynamically signals theantenna port and SCID of the corresponding D-PDCCH.
 6. The method ofclaim 5, wherein the user equipment (UE) first decodes the D-PDCCHconfiguration-grant to obtain the antenna Port (AP) and SCIDinformation, then proceeds to decode D-PDCCH.
 7. The method of claim 5,wherein the user equipment (UE) is configured by higher layer signalingto receive D-PDCCH with rank greater than 1, using spatial multiplexingon antenna ports (7, . . . , 7+R−1) where R is a positive integer with aSCID of
 0. 8. The method of claim 5, wherein the transmission rank,antenna ports and SCID are dynamically configured with the D-PDCCHconfiguration-grant.
 9. A method of operating a user equipment (UE),comprising: receiving a downlink (DL) assignment on a DemodulationReference Signal (DMRS)-based physical downlink control channel(D-PDCCH) and if the user equipment (UE) detects via physical controlformat indicator channel (PCFICH) on its legacy control region that thenumber of OFDM symbols is strictly smaller than the starting symbol forD-PDCCH, then the user equipment (UE) shall assume that a physicaldownlink shared channel (PDSCH) is also present on the OFDM symbolsbetween symbols between the last symbol of the legacy PDCCH region andthe first symbol of the D-PDCCH.
 10. A method of operating a userequipment (UE), comprising: receiving a downlink (DL) assignment on aDemodulation Reference Signal (DMRS)-based physical downlink controlchannel (D-PDCCH) and if the user equipment (UE) detects via physicalcontrol format indicator channel (PCFICH) on its legacy control regionthat the number of OFDM symbols is strictly smaller than the startingsymbol for D-PDCCH, then the user equipment (UE) shall assume that aphysical downlink shared channel (PDSCH) is also present on the OFDMsymbols between symbols between the last symbol of the legacy PDCCHregion and the first symbol of the D-PDCCH, wherein the user equipment(UE) is configured to decode a downlink grant in D-PDCCH on a firstantenna port, and decode an uplink grant on a second antenna port. 11.The method of claim 1, wherein the parameter is a scrambling sequence ID(SCID) of 0 or
 1. 12. A user equipment (UE) comprising: a memory; atransceiver configured to receive a Demodulation Reference Signal(DMRS)-based physical downlink control channel, wherein the DMRS-basedphysical downlink control channel is scrambled based on a parameterconfigured via Radio Resource Control (RRC) signaling; and a processorcoupled to the memory and the transceiver, the processor beingconfigured to decode an uplink grant received via the DMRS-basedphysical downlink control channel, wherein the UE is configured totransmit data on an uplink shared channel (UL-SCH) in response to theuplink grant.
 13. The UE of claim 12, wherein the parameter is ascrambling sequence ID (SCID) of 0 or
 1. 14. The UE of claim 12, whereinthe processor is further configured to decode the uplink grant using theparameter configured via RRC signaling.
 15. A method comprising:receiving, by a user equipment (UE), a Demodulation Reference Signal(DMRS)-based physical downlink control channel (D-PDCCH), wherein theD-PDCCH is scrambled based on a parameter configured via Radio ResourceControl (RRC) signaling; decoding, by the UE, an uplink grant receivedvia the DMRS-based physical downlink control channel; and transmitting,by the UE, data on an uplink shared channel (UL-SCH) in response to theuplink grant.
 16. The method of claim 15, wherein the parameter is ascrambling sequence ID (SCID) of 0 or
 1. 17. The method of claim 15,further comprising decoding the uplink grant using the parameterconfigured via RRC signaling.